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docs: path-lookup: i_op->follow_link replaced with i_op->get_link

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follow_link has been replaced by get_link() which can be
called in RCU mode.

see commit: commit 6b2553918d ("replace ->follow_link() with
new method that could stay in RCU mode")

Signed-off-by: Fox Chen <foxhlchen@gmail.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20210527091618.287093-8-foxhlchen@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Fox Chen 2021-05-27 17:16:12 +08:00 committed by Jonathan Corbet
parent d2d3dd5ecc
commit 4a00e4bd59
1 changed files with 5 additions and 7 deletions
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12
Documentation/filesystems/path-lookup.rst
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@ -1060,13 +1060,11 @@ filesystem cannot successfully get a reference in RCU-walk mode, it
must return ``-ECHILD`` and ``unlazy_walk()`` will be called to return to
REF-walk mode in which the filesystem is allowed to sleep.
The place for all this to happen is the ``i_op->follow_link()`` inode
method. In the present mainline code this is never actually called in
RCU-walk mode as the rewrite is not quite complete. It is likely that
in a future release this method will be passed an ``inode`` pointer when
called in RCU-walk mode so it both (1) knows to be careful, and (2) has the
validated pointer. Much like the ``i_op->permission()`` method we
looked at previously, ``->follow_link()`` would need to be careful that
The place for all this to happen is the ``i_op->get_link()`` inode
method. This is called both in RCU-walk and REF-walk. In RCU-walk the
``dentry*`` argument is NULL, ``->get_link()`` can return -ECHILD to drop out of
RCU-walk. Much like the ``i_op->permission()`` method we
looked at previously, ``->get_link()`` would need to be careful that
all the data structures it references are safe to be accessed while
holding no counted reference, only the RCU lock. Though getting a
reference with ``->follow_link()`` is not yet done in RCU-walk mode, the